Chair backrest

ABSTRACT

Provided is a two-sectional ergonomic chair backrest comprising a vertical backrest support, an upper back unit releasably secured to the backrest support, a waist unit including a front waist member, an intermediate frame, and a rear plate releasably secured to the backrest support, and a bent, resilient connecting member including a lower portion releasably secured to the waist member and the frame, and an upper portion releasably secured to the backrest support such that in response to the waist of a seated person urged against the waist unit, the connecting member is elastically deformed so as to provide a great degree of comfort to the waist.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to ergonomic chair backrests and moreparticularly to such a backrest consisting of two cooperative waist andback sections so as to bring a degree of comfort to, particularly thewaist of a seated person.

2. Related Art

A conventional chair backrest is a one-piece component. Also, most priorart ergonomic chair backrests emphasize the degree of comfort to theback of a seated person rather than the waist. A small number of priorart chair backrests incorporating a mechanism for bringing a degree ofcomfort to the waist of a seated person. However, such prior mechanismscannot fit waists of different seated people. Thus, backrests withheight-adjustable waist pads are developed, in which a waist pad isattached to a backrest of a chair by elastic bands. However, suchconventional art suffers from some disadvantages. For example, elasticbands ultimately lose its elasticity. Another conventional backrest isprovided with a waist support cooperated with a transmission member.Such conventional backrests are typically, relative complex inconstructions and costly to manufacture. Hence, a need for improvementstill exists.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide atwo-sectional ergonomic chair backrest which has simply constructionsand structures.

The chair backrest according to the present invention comprises avertical backrest support; an upper back unit formed of an elastomericmaterial and releasably secured to the backrest support; a waist unitincluding a front waist member formed of an elastomeric material, anintermediate frame, and a rear plate releasably secured to the backrestsupport, and a bent, resilient connecting member including a lowerportion releasably secured to the waist member and the frame, and anupper portion releasably secured to the backrest support. By utilizingthis chair backrest, in response to the waist of a seated person urgedagainst the waist unit, the connecting member is elastically deformed soas to provide a great degree of comfort to the waist.

In one aspect of the present invention, the backrest support comprises aplurality of upper hollow locating cylinders, and the back unitcomprises a plurality of rear pegs shaped to neatly insert into thelocating cylinders for fastening.

In another aspect of the present invention, the frame comprises aplurality of peripheral locating holes, and the plate comprises aplurality of peripheral hollow locating cylinders shaped to neatlyinsert into the locating holes for fastening.

In yet another aspect of the present invention, the upper portion of theconnecting member is disposed in a recess between the back unit and thebackrest support, and the lower portion of the connecting member isdisposed in a recess between the frame and the plate.

The above and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptiontaken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a preferred embodiment of a chair backrestaccording to the invention;

FIG. 2 is a perspective view of the assembled backrest of FIG. 1;

FIG. 3 is a side view of the backrest of FIG. 2 assembled with a chair;

FIG. 4 is a front view of the backrest of FIG. 2;

FIG. 5 is a schematic sectional view taken along sectional line I ofFIG. 4; and

FIG. 6 is a view similar to FIG. 5, where a force is exerted onto thewaist unit and the connecting member is elastically deformed inresponse.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, there is shown a chair backrest constructedin accordance with a preferred embodiment of the invention. The backrestcomprises a waist unit 1, a bent, resilient connecting member 2, anupper back unit 3 and a substantially rectangular, vertical backrestsupport 4 and a plurality of fasteners 5 such as screws or the like.

The waist unit 1 includes a front waist member 11 formed of anelastomeric material, an intermediate, rectangular frame 12 having aplurality of locating holes 122 on its periphery and a plurality ofapertures 121 in its upper, central portion, and a rear, rectangularplate 13 having a plurality of hollow locating cylinders 131 shaped toneatly insert into the locating holes 122 for fastening.

The upper back unit 3 includes a front backrest member 31 formed of anelastomeric material, and a curved rear portion 32 having a plurality ofpegs (not shown) shaped to neatly insert into the locating cylinders 43.

The backrest support 4 is formed integrally and includes, from top tobottom, a plurality of hollow locating cylinders 43 arranged on theupper and side edges of an upper section, a projection 41, a pluralityof threaded holes 42 arranged as a shape of rectangle around theprojection 41, and a forwardly projected bracket 44.

The bent, resilient connecting member 2 includes a plurality of threadedholes, an upper portion disposed in a recess of the upper section of thebackrest support 4, and a lower portion disposed in a recess behind theframe 12 and fastened between the frame 12 and the plate 13 by screwingfasteners 5 through apertures on the lower portion of the connectingmember 2 into the apertures 121 and by inserting locating cylinders 131of the plate 13 into the locating holes 122 of the frame 12.

In assembly, referring to FIGS. 1 and 3, the projection 41 is neatlyinserted into a central hole of the connecting member 2 attached to thewaist unit 1 for positioning. The plurality of fasteners 5 are securedthrough apertures on the upper portion of the connecting member 2 to theholes 42 of the backrest support 4 for fastening. In addition, pegs ofthe back unit 3 are inserted into the hollow locating cylinders 43 sothat the back unit 3 and the backrest support 4 are assembled together.The forwardly projected bracket 44 is secured to a bottom of a seat in amanner well known in the art.

Referring to FIGS. 3, 4, 5, and 6, in response to the waist of a seatedperson urged against the waist unit 1 as indicated by arrows, theconnecting member 2 is elastically deformed. As a result, a great degreeof comfort to the waist of the person is brought by the ergonomic waistunit 1.

While the invention herein disclosed has been described by means ofspecific embodiments, numerous modifications and variations could bemade thereto by those skilled in the art without departing from thescope and spirit of the invention set forth in the claims.

1. A chair backrest comprising: a vertical backrest support; an upperback unit formed of an elastomeric material and releasably secured tothe backrest support; a waist unit including a front waist member formedof an elastomeric material, an intermediate frame, and a rear platereleasably secured to the backrest support, and a bent, resilientconnecting member including a lower portion releasably secured to thewaist member and the frame, and an upper portion releasably secured tothe backrest support.
 2. The chair backrest of claim 1, wherein thebackrest support comprises a plurality of upper hollow locatingcylinders, and the back unit comprises a plurality of rear pegs shapedto neatly insert into the locating cylinders for fastening.
 3. The chairbackrest of claim 1, wherein the frame comprises a plurality ofperipheral locating holes, and the plate comprises a plurality ofperipheral, hollow locating cylinders shaped to neatly insert into thelocating holes for fastening.
 4. The chair backrest of claim 1, whereinthe upper portion of the connecting member is disposed between the backunit and the backrest support, and the lower portion of the connectingmember is disposed between the frame and the plate.